An elevator comprises an elevator car, lifting machinery, ropes, and a counter weight. The elevator car is supported on a sling surrounding the elevator car. The lifting machinery comprises a traction sheave, a machinery brake and an electric motor being connected via a shaft. The electric motor is used to rotate the traction sheave and the machinery brake is used to stop the rotation of the traction sheave. The lifting machinery is situated in a machine room. The lifting machinery moves the car upwards and downwards in a vertically extending elevator shaft. The sling and thereby also the elevator car is carried by the ropes, which connect the elevator car over the traction sheave to the counter weight. The sling of the elevator car is further supported with gliding means at guide rails extending in the vertical direction in the elevator shaft. The gliding means can comprise rolls rolling on the guide rails or gliding shoes gliding on the guide rails when the elevator car is moving upwards and downwards in the elevator shaft. The guide rails are supported with fastening brackets at the side wall structures of the elevator shaft. The gliding means engaging with the guide rails keep the elevator car in position in the horizontal plane when the elevator car moves upwards and downwards in the elevator shaft. The counter weight is supported in a corresponding way on guide rails supported on the wall structure of the elevator shaft. The elevator car transports people and/or goods between the landings in the building. The elevator shaft can be formed so that the wall structure is formed of solid walls or so that the wall structure is formed of an open steel structure.
The cross section of the guide rails has normally the form of a letter T. The horizontal branch of the letter T is attached to support brackets being attached to the wall structure of the elevator shaft. The vertical branch of the letter T forms three gliding surfaces for the gliding means. There are thus two opposite side gliding surfaces and one front gliding surface in the guide rail. The gliding means comprises normally a frame part and a gliding part. The horizontal cross-section of the gliding part has the form of a letter U so that the inner surface of the gliding part sets against the three gliding surfaces of the guide rail. The horizontal cross section of the frame part has also a U-shaped section surrounding the gliding part on three sides. The frame part comprises further outwardly extending flanges at the bottom of the letter U for attaching the gliding means to the car sling. There are elasticity means between the gliding part and the frame part in order to isolate the gliding part from the frame part.
The guide rails are formed of guide rail elements of a certain length. The guide rail elements are connected in the installation phase end-on-end one after the other in the elevator shaft. It is difficult and time consuming to align two consecutive guide rail elements so that there is no mismatch between the ends of the guide rail elements. The alignment is done by using a long straight metallic square bar which is placed against the front surface of the guide rails. The square bar is positioned over the joint of two consecutive guide rail elements so that the upper portion of the square bar extends in the vertical direction along the upper guide rail and the lower portion of the square bar extends in the vertical direction along the lower guide rail. When this square bar is in position, a source of light is placed on one side of the guide rail and the mechanic looks at the joint from the opposite side of the guide rail. Misalignment of two consecutive guide rail elements, means that there is a gap between the reference square bar and the guide rail elements. This misalignment can be observed by the technic looking at the joint by the light passing through the gap. The alignment is done by forcing and/or moving the support bracket into a desired position with a hand tool after which the bolts are tightened in order to keep the guide rail element in the desired position. The quality of the alignment will vary depending on the mechanic who is doing the alignment.